mRNA levels in the developing aleurone and starchy endosperm in wild type and a high lysine (lys 3a) mutant of barley

We have analysed the effects of the lys 3a mutation on mRNA levels in the developing aleurone and starchy endosperm. The objective was to investigate whether the increase in non‐hordein gene mRNA is a compensation for decreased hordein mRNA levels or if the increase is a result of a selective transcriptional or posttranscriptional regulation of specific genes. Our results show that protein Z and β‐amylase which are downregulated by the lys 3a mutation are affected only in the starchy endosperm. In contrast, mRNA levels for the chymotrypsin inhibitors (CI‐1, CI‐2) are enhanced in the aleurone as well as in the starchy endosperm. The two isoform inhibitor genes of CI‐1 (CI‐1A, CI‐1B) are differentially affected in the aleurone by the lys 3a mutation. The lys 3a gene enhances mRNA levels of two aleurone‐specific genes. Together, these findings suggest that the lys 3a gene encodes or affects a regulatory factor which specifically modulates mRNA levels of several genes in different seed tissues.